β­1,3­N­acetylglucosaminyltransferase 6 (β3GnT6) transfers N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to N-acetylgalactosamine (GalNAc). β3GnT6 is also known as the core 3 synthase, because it creates the core 3 oligosaccharide structure in the mucin-type O-glycan, GlcNAcβ1­3GalNAcα1­serine/threonine (1). Core 3 synthase is a type II transmembrane protein, and is localized to stomach, small intestine and colonic tissues (1). It has long been known that synthesis of the core 3 structure is down-regulated in colonic cancer cells (2) and it has been shown that the expression of β3GnT6 is also down-regulated (1). Colonic cancer cells transfected with β3GnT6 have reduced metastatic potential compared to non-transfected cells, and when injected into mice show decreased tumor formation (3). Pancreatic cancer cells transfected with β3GnT6 show a similar phenotype, which has been attributed to the addition of core3 O-glycans to α2β1 integrin (4).